Water fitness is fantastic at building strength as water offers natural resistance. Any exercise done in water is going to be more effective at building strength than if you had performed the same exercise on land. The reason is that water is about 12 to 14 times denser than air. Due to the natural resistance of water, exercises such as walking in water can burn twice as many calories an hour than walking on land. Additionally, the water provides support for the body, making it less likely for a muscle, bone or joint to get injured. Water supports up to 80% of your weight, thereby causing less strain on the joints, back, and torso when compared to exercises performed on land.